Split `user` into a chat-facing entity and an authentication-facing entity.

The taxonomy is now as follows:

* A _login_ is someone's identity for the purposes of authenticating to the service. Logins are not synchronized, and in fact are not published anywhere in the current API. They have a login ID, a name and a password.

* A _user_ is someone's identity for the purpose of participating in conversations. Users _are_ synchronized, as before. They have a user ID, a name, and a creation instant for the purposes of synchronization.

In practice, a user exists for every login - in fact, users' names are stored in the login table and are joined in, rather than being stored redundantly in the user table. A login ID and its corresponding user ID are always equal, and the user and login ID types support conversion and comparison to facilitate their use in this context.

Tokens are now associated with logins, not users. The currently-acting identity is passed down into app types as a login, not a user, and then resolved to a user where appropriate within the app methods.

As a side effect, the `GET /api/boot` method now returns a `login` key instead of a `user` key. The structure of the nested value is unchanged.

1 files changed, 10 insertions, 5 deletions

diff --git a/src/message/history.rs b/src/message/history.rs
index d4d4500..2abdf2c 100644
--- a/src/message/history.rs
+++ b/src/message/history.rs
@@ -1,7 +1,7 @@
 use itertools::Itertools as _;
 
 use super::{
-    Id, Message,
+    Message,
     event::{Deleted, Event, Sent},
 };
 use crate::event::Sequence;
@@ -13,10 +13,6 @@ pub struct History {
 
 // State interface
 impl History {
-    pub fn id(&self) -> &Id {
-        &self.message.id
-    }
-
     // Snapshot of this message as it was when sent. (Note to the future: it's okay
     // if this returns a redacted or modified version of the message. If we
     // implement message editing by redacting the original body, then this should
@@ -26,6 +22,15 @@ impl History {
         self.message.clone()
     }
 
+    pub fn as_of<S>(&self, sequence: S) -> Option<Message>
+    where
+        S: Into<Sequence>,
+    {
+        self.events()
+            .filter(Sequence::up_to(sequence.into()))
+            .collect()
+    }
+
     // Snapshot of this message as of all events recorded in this history.
     pub fn as_snapshot(&self) -> Option<Message> {
         self.events().collect()